In order to store data, including digital electronic data, such as back-up data from a server computer device, it is known to use magnetic tape data storage cartridges comprising one or a pair of rotatable reels and an elongate band of magnetic tape. One reason for using such tape data storage cartridges is to make back-up copies of important data. Another reason for using such tape data storage cartridges is for use in archiving data.
Tape drive apparatus is known in the prior art. Such prior art tape drive apparatus is known, in some examples, to comprise drive means to drive movement of an elongate magnetic tape in order to transfer tape between two rotatable reels on a tape data storage cartridge. Transfer of magnetic tape passes the elongate tape past a magnetic read/write head enabling data to be written to, or read from, the magnetic tape.
An alternative prior art tape drive arrangement is illustrated in FIG. 1. FIG. 1 illustrates a linear tape drive 104 and tape data storage cartridge 101. Tape data storage cartridge 101 comprises one rotatable reel 102 comprising a reel of an elongate band of magnetic tape 103. On placing tape data storage cartridge 101 into linear tape drive 104 the elongate band of magnetic tape is introduced to the linear tape drive 104. One or a plurality of guides 105 are used to thread the tape from cartridge reel 102 to tape drive reel 106. The threaded tape is thus presented to a read/write head 107 enabling data to be read from, or written to, tape 103. FIG. 1 illustrates a gap between read/write head and tape 103, this is for clarity, in practice, tape 103 is in contact with the read/write head 107 to enable reading or writing of data.
FIG. 2A and FIG. 2B illustrate diagrammatic representations of the structure of a typical read/write head assembly known to be used in prior art tape drives. Referring to FIG. 2A, a section through the width of tape 103 is shown. The read/write head 107 comprises a plurality of read/write head elements 201 assembled to form a multi-channel head assembly which is maintained in contact with the surface of tape 103 by tension in the tape. Each of the read/write head elements 201 is configured to permit reading/writing of data to physical tracks on tape 103. The read/write head 107, in some prior art examples, is configured for limited transverse movement across the width of tape 103 as indicated by arrow 202. In the prior art, this movement is limited to movement substantially within the width of tape 103 to enable reading/writing of data to physical tracks on tape 103. It is not known in the prior art for read/write head 107 to be translationally displaced beyond the periphery of the tape width.
FIG. 2B illustrates a diagrammatic representation of the read/write head illustrated in FIG. 2A, FIG. 2B illustrating a top view looking down on the length of elongate tape 103. FIG. 2A illustrates a side view of this arrangement. Referring to FIG. 2B, arrow 203 illustrates the possible directions of tape motion past read/write head 107. In both FIG. 2A and FIG. 2B a gap between tape 103 and read/write head elements 201 is illustrated for clarity, in practice the tape surface is in contact with the read/write head elements 201.
Considering the prior art tape drive arrangements described above, the head elements 201 are maintained in contact with the tape 103. As tape 103 moves past the read/write head 107, the head is subject to wear. As the tape 103 is maintained in contact with read/write head elements 201, this wear is also present during tape searching, such as in a fast forward or rewind mode. Particularly considering use of prior art tape drives in archiving arrangements where tape data is rapidly searched to locate a required data set, the ratio of tape movement to data access is significantly higher than in, for example, back-up applications. Accordingly, the serviceable lifetime of such prior art tape drives is reduced due to increased wear of read/write head elements 201 during searching.
There is therefore a technical problem with prior art tape drives in that maintaining contact of tape 103 with read/write head elements 201 during tape searching significantly decreases the lifetime of the read/write head 107.
One solution to this problem known in the prior art is to loosen the tape tension. This is unsatisfactory and causes problems with tape threading and accurate reading and writing of data to the tape. Another solution known in the prior art is to introduce a stream of air between the read/write head 107 and tape 103 during searching to lift the tape 103 from contact with the read/write head elements 201. This is a complex solution significantly increasing the complexity of the tape drive apparatus and the associated cost of manufacture.
JP 08273250 A discloses a tape recorder with excess tape contact pressure prevention during forward/reverse operation. Whilst relieving excess tape contact pressure with a head is considered, this prior art disclosure does not overcome the problems of how to maintain tape tension during tape search whilst eliminating head wear during search.
U.S. Pat. No. 5,179,486 discloses apparatus operable to align a record/play back head with respect to different parallel tracks of a tape. Means is provided to move the record/play back head transversely with respect to the tape in order to align the record/play back head with respect to tracks on the tape. However, this movement is within the width of the tape and this prior art disclosure does not consider substantially complete displacement of the read/write head from the tape surface.
In order to improve the service life time of tape drives, apparatus for reducing read/write head element wear, particularly during searching of a tape, will be of benefit.